摘要:

Cation distribution at 1600 K in the system Fe3O4‐FeA12O4was derived from Seebeck coefficient measurements assuming that the aluminum distribution behaved according to the thermodynamic model proposed by O'Neill and Navrotsky. Approximately 10% of the aluminum resides tetrahedrally. This system provides a good test of thermodynamic model

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09635.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A fine, uniform A12O3‐SiO2powder was prepared by heterocoagulation of narrow Al2O3and SiO2powders. This composite powder was dispersed, compacted, and fired in air at 900° to 1580°C for 1 to 13 h. Full density was achieved at 1550°C with the formation of a mullite phase. Relative densities of 83% and 98% (0.3 μm grain size) were measured for samples sintered at 1200°C for 13 h and at 1400°C for 1 h, respe

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09636.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Polycrystalline TiB2specimens of 3 μm average grain size but free of lamellar precipitates were compression‐tested to 1900°C and 500 MPa. No plastic yielding was detected. Under such conditions, most other structural ceramics do exhibit yield behavior. The results suggest the existence of a high Peierls stress, presumably related to Ti—B bonding. This finding contrasts with a report on ZrB2in which resistance to yielding was attributed to lamellar precipi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09637.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Calcia‐stabilized zirconia, CSZ (7.5 wt% CaO), with impurities of A12O3, SiO2, MgO, Fe2O3, and TiO2, was sintered in air at 1783 K for times (t) up to 230 h. The microstructure consisted of grains of CSZ with small amounts of pores and a CaO‐Al2O3‐SiO2eutectic. Grain diameters grew in proportion to t1/3. The results are consistent with a mechanism in which grain growth is limited by diffusion of Zr4+ions through the liquid eut

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09638.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The fraction of four‐coordinated boron was observed to increase from 10% in a rapidly cooled aluminum borosilicate glass fiber to 16% in the same fiber after it was annealed; the refractive index also increased. The index of the annealed fiber agreed with that of the bulk glass. Crystallization was not observed in the annealed fiber. It is concluded that boron coordination is temperature dependent and associated with structural relaxatio

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09639.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Improved rheological stability in silicon‐yttria slurries for sinterable reaction‐bonded silicon nitride was obtained by treating casting slips with NH4+‐ion‐exchange resin. The substitution of NH4+ions for flocculating ions (Ca2+or Y3+) appears to be the principal factor leading to more time‐stable pseudoplastic yield stress and vi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09640.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09642.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09643.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09644.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A tentative phase diagram for the system Al203‐Nd2O3is presented. Three compounds were obtained: aβ‐A12O3‐type compound, the perovskite NdAlO3, and Nd4Al2O9. The perovskite melts congruently (mp 2090°C), and the two other compounds exhibit incongruent melting behavior:β‐Nd/Al2O3, mp 1900°C; Nd4Al2O9, mp 1905°C. Two eutectics exist with the following compositions and melting points: 80 mol% Al2O3, 1750°C; 23 mol% Al2O3,1800°C. Nd4Al2O9 decomposes in the solid s

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1985.tb09645.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY